J.P.
When my son was around 6 months, we went in an RV from Texas to California and back. We had a small RV. What we did was change the table into the bed by dropping the table down. Then, I just faced him to the rear and buckled him in his car seat at the table spot closest to the window. We had also rigged up a board (a 1"x12" about 4 ft long) that went the length of the table seats so that we could also lay down on the bed/table area without rolling off while driving. For the most part, he did just fine in the car seat. I did take him out while driving to change him and give him a bottle but for the most part, I could lay there with him (or his sister could entertain him) and we were still in a playpen type of area so we didn't have to worry! Lots of books and toys and little baby snacks will make the trip easier!!
Good luck!